E. M. Fry, J. Org. Chem., 15, 802 (1950) and T. Kagiya et al., Polymer Letters, 4, 257 (1966) have shown that oxazoline rings are opened by carboxylic acids, thus producing the corresponding esters of the acid.
Bis-oxazolines and -oxazines suitable for use in making the compounds of the present invention have been disclosed by Tomalia and Paige in U.S. Pat. No. 3,563,920 and by Tomalia and Sheetz in U.S. Pat. No. 3,763,177.
The use of bis-oxazolines as cross-linking and curing agents for carboxyl-containing polymers has been disclosed by Thill in U.S. Pat. No. 3,758,629.
Fukui et al., U.S. Pat. No. 3,476,712 teach that bis-oxazolines react when heated with dicarboxylic acids to produce polymeric ester-amides.